Machines have been devised for cutting and milling various shapes or patterns in metal surfaces and the like. However, the formation of tread patterns in a tire mold presents particular problems in that the mold is curved both in a circumferential direction and may have any number of patterns formed along different radii of curvature in a direction transversely of its circumference including both positive and negative radii of curvature. Yet, to be economically feasible, the milling operation is most desirably carried out at a single station or machine in which the mold can be clamped in place with a single tool holder which is caused to describe different arcs or radii of curvature automatically in response to a pattern to be traced as the mold is rotated at a predetermined but variable rate of speed in either direction of rotation. Further, it is desirable that the tool be capable of oscillation through a selected radius of curvature, positive or negative, either along a vertical or horizontal surface of the mold and in such a way as to require replacement or substitution only of the cutting tool itself to conform to various widths or thicknesses and shapes of a pattern to be formed while permitting adjustment of the radius or arc described by the tool. Further, the machine should be so designed as to be responsive to various types of pattern tracing systems and wherein the tool itself is capable of traversing different arcs in response to linear impulses or speed control signals.